Is Amazon rainforest becoming net CO2 emitter?

A new study in the journal Science shows that the Amazon suffered a serious drought last year—making for two severe droughts in the world’s biggest rainforest within five years, and raising disturbing implications for global climate. While the Amazon normally absorbs huge amounts of CO2, droughts cause the reverse effect—with the forests releasing emissions as dead trees decay. Emissions from last year’s drought may exceed the 5 billion tons of CO2 that the last drought in 2005 is believed to have released. This is roughly equal to the annual emissions of the United States.

Lead author Dr. Simon Lewis, from the University of Leeds, said: “Having two events of this magnitude in such close succession is extremely unusual, but is unfortunately consistent with those climate models that project a grim future for Amazonia.” The drought is particularly worrying as it would normally be a “once in a century” event, he said. “It’s difficult to detect patterns from just two observed droughts, but to have them close together is concerning,” he told BBC News.

Co-author Dr. Paulo Brando, from Brazil’s Amazon Environmental Research Institute (IPAM), warned that research methods may actually understate the problem: “Our results should be seen as an initial estimate. The emissions estimates do not include those from forest fires, which spread over extensive areas of the Amazon during hot and dry years. These fires release large amounts of carbon to the atmosphere.”

Research leader Lewis is the scientist who won an apology from London’s Sunday Times newspaper last year over the so-called “Amazongate” affair. (Environmental Data Interactive, Feb. 4; BBC News, Feb. 3)

In the Amazongate matter, Sunday Times science editor Jonathan Leake, hoping for a sequel to the Glaciergate scandal, accused the Intergovernmental Panel on Climate Change (IPCC) of making a “bogus rainforest claim” when it cited a World Wildlife Fund (WWF) report warning that up to 40% of the Amazon could be “drastically” affected by climate change. The Times was forced to retract the story when the WWF data was vindicated. (Mongabay, Feb. 3, 2010)

See our last posts on global climate change and the struggle for the Amazon.

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